Added allowDefaultLogoutUrl config to optionally ignore non-custom logoutUrl

...n-html5/imports/ui/components/meeting-ended/component.jsx

...tton-html5/imports/ui/components/meeting-ended/service.js

bigbluebutton-html5/imports/ui/services/auth/index.js

bigbluebutton-html5/imports/utils/logoutRouteHandler.js

bigbluebutton-html5/private/config/settings.yml